Regarding the formation of abnormal structure and of the soft spots frequently found in carburized hyper-eutectoid steels, many important investigations have been done and now two hypotheses are proposed for the cause of the formation, namely (1) oxygen and (2) high purity iron. The oxygen hypothesis, which is known for ages, seems to be based upon the facts that the structure of the steel becomes abnormal when it is carburized with an oxygen-containing carburizer, such as carbon monoxide gas, etc., while the structure of the same steel is normal when the carburizer is hydrocarbon, such as methane or benzene, and also that the incompletely deoxidized steel shows the abnormal structure. The high purity iron hypothesis, which is developed recently in germany, is based upon the fact that the structure of the chemically pure iron, such as carbonyl or electrolytic iron becomes abnormal after carburization, coalescence of the eutectoid cementite being remarkable in this case.
In order to check the above hypotheses, the present authors repeated the experiments done by previous workers and arrived at the conclusion that the both of them are experimentally correct. Hence the authors made some further experiments with their own idea, and proposed a new explanation for the oxygen hypothesis that is the oxygen acts as purifier for the normal steel which contains more basic elements than iron. Thus, the oxygen theory in essence, agrees well with the high purity iron theory the difference being only the mode of expression.

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X-ray analyses of the phases existing in the Ni-Sb system have been carried out, and the following iesults were obtained.
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The most noticeable feature in the present investigation is the finding of super-structure phase α' in the solid solution of α.

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The procedure of preparing single crystals of nickel and copper by the method of slow solidification, and the apparatus for producing and observing light figures of crystals were described. Single crystals of nickel and copper were etched with aqueous solutions of acids and salts, of various concentrations, for different time-intervals, and light figures on the three principal crystal planes (100), (110), and (111) were observed and examined in detail in view of utilizing them for determining the orientations of the said metal crystals. The symmetry characteristics of the light figures are naturally invariable, while their forms may, in general, vary with an etching reagent, its temperature, and the time of etching. The most suitable light figures for the determination of the crystal orientation were found to be those on (100) planes, except a few cases for nickel crystals.

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A new apparatus for measuring the running quality of molten metals and alloyi has been designed by the authors. This apparatus consists of three parts; a metallic mould having a straight measuring canal about 150cm long whose cross section is an inverted equilateral triangle a side of which is 7mm, a sand mould of an inverted circular cone type which acts as a reservoir for the molten metal and a metallic mould having a downgate and a runner which leads to the measuring canal and acting as a part connecting the sand mould reservoir and the measuring canal.
To equalize the statical head of the molten charge throughout the test, a stopper is used in the sand mould. After filling the sand mould with the molten charge, this is removed and the charge is poured into the test mould. Assuming that the metal completely fills the measuring canal, the height difference in the reservoir is only about 2mm. The measuring canal is made by assembling two steel angles and one flat steel, and are coated with very fine alundum cement on their inner surfaces to prevent the metal from flowing in spherical drops because of extreme smoothness of the inner surfaces. The temperature of the mould is measured by inserting mercury thermometers into holes in the moulds, which are maintained at 70°. The pouring temperature is measured by an alumel-chrotnel thermocouple placed in the steel protecting tube.
By using this apparatus, the running quality of pure magnesium and the influence of a limited content of aluminium, zinc, manganese or copper on magnesium, and also the running quality of four kinds of industrial magnesium alloy, Elektron are studied. The results obtained are as follows:
The running quality of pure magnesium decreases by an addition of 5% aluminium, but increases by 10% addition The increasing effect of 30% aluminium is very marked. Zinc up to 2% gradually decreases the running quality of pure magnesium, but no further decrease is observable between 2% and 3%. A small amount of manganese within the extent added to the industrial magnesium alloy has no influence. An addition of copper up to 0.5 % gradually decreases the running quality of pure magnesium, but 1% copper suddenly decreases it. These phenomena should be attributed to many factors, such as casting conditions and inherent properties of alloying elements and others, but should be explained by the solidification theory and the equilibrium diagram as follows: the running quality of magnesium gradually decreases as an alloying element dissolves in magnesium and consequently the solidification range increases, showing a minimum value at the composition of a saturated solid solution and then gradually increases as the solidification range decreases, showing a maximum value at a composition corresponding to a eutectic, an intermetallic compound or others which have a constant temperature of solidification as does a pure metal, but as the equilibrium condition practically does not exist, the effect of supercooling and crystal segregation should be taken into account in considering the experimental results.

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Theequilibrium diagram of the Al-Mo (Al side) System is determined as shown in Fig. I. Purity of material employed is given in Table I. As the ordinary thermal analysis was not seemed sensitive enough to determine the liquidus curve and the peritectic temperature, the former was detemined by the chemical analysis of liquid phase which was in coexistence with the primary compounds, and the latter was determined from microstructure of specimens quenched from a supposed range of temperature. Solubility of Mo in solid Al could not be detected by back reflection X-ray analysis nor by the change of hardness after quenching and tempering. Composition of intermetallic compound was estimated by the chemical analysis of insoluble constituents of Al-Mo alloys.

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Sb and As sind die in Rohzinn gewöhnlich befindlichen Verunreinigungen. Man kan As nach Trockenraffinationsverfahren bis zu einen gewisse Grade beseitigen, währeral Sb gar nicht.
Die Ergebnisse dieses Versuchs sind wie folgt: Mit dem Sb-Gehalt von 0.5% wird der Passivwerden der Zinnanode nicht so inerkwürdig beeinflusst, aber mit 5% Sb trat die Passivität ziemlich schnell ein. Weitere Vermehrung bis zu 10% zeigt nur geringen Effekt. Die Löslichkeit von Sb in Sn ist bei Zimmertemperatur ungefähr 8%, so scheint es, dass das in fester Lösung befindliche Sb hauptsächlich passivierend bewirkt, während die Verbindung Sn Sb fast nicht. Bei einem hochgesteigerten Anodenpotentiale (passive Anode) stellt die Sb-haltige Zinnanode eine Erscheinung dar, die als eine anderer Passivität angenothinen werden. Die Ursache davon ist wahrscheinlich wie folgend: Wegen des hochwerdenden Anodenpotentials löst das in Sn gelöste Sb elektrochemisch, das aber sofort hydrolysiert, stopfend die Poren in primär gebildete Bedeckungsschicht mit Hydrolysenprodukte.
As scheint auch beförderend auf die Passivierung bewirken.

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